10 Essential Python Flow‑Control Examples

🚀 Introduction: Flow control is a core concept in programming that determines how code blocks are executed; the following ten Python examples cover conditional branching, looping, and error handling.

1️⃣ Conditional statement (if…elif…else)

score = 85
if score >= 90:
    print("优秀")
elif score >= 80:
    print("良好")
elif score >= 60:
    print("及格")
else:
    print("不及格")

2️⃣ Nested conditionals

age = 22
is_student = True
if age < 18:
    status = "未成年人"
elif age < 60 and is_student:
    status = "在校学生"
else:
    status = "社会人士"
print(status)

3️⃣ Ternary operator

grade = 78
result = "合格" if grade >= 60 else "不合格"
print(result)

4️⃣ For‑loop over a sequence

fruits = ['apple', 'banana', 'cherry']
for fruit in fruits:
    print(fruit)
# Output:
# apple
# banana
# cherry

5️⃣ Counting loop with range()

for i in range(1, 6):
    print(i)
# Output:
# 1
# 2
# 3
# 4
# 5

6️⃣ While‑loop as a conditional loop

count = 0
while count < 5:
    print(count)
    count += 1
# Output:
# 0
# 1
# 2
# 3
# 4

7️⃣ Controlling loops with break and continue

for number in range(1, 11):
    if number % 2 == 0:
        continue  # skip even numbers
    if number == 5:
        break     # stop when number reaches 5
    print(number)
# Output:
# 1
# 3

8️⃣ List comprehension with a condition

numbers = [1, 2, 3, 4, 5, 6]
even_numbers = [num for num in numbers if num % 2 == 0]
print(even_numbers)  # Output: [2, 4, 6]

9️⃣ Exception handling (try…except…finally)

try:
    open('non_existent_file.txt', 'r')
except FileNotFoundError:
    print("文件未找到！")
finally:
    print("无论是否发生异常，这段代码都会被执行。")

10️⃣ pass as a placeholder

for _ in range(5):
    if _.is_prime:  # hypothetical attribute
        pass  # no operation, placeholder for future code
    else:
        print(_.value)  # print non‑prime values

🎯 Conclusion: By studying and practicing these ten examples, readers should gain a deeper understanding of Python's conditional branches, loop controls, and exception handling, which are essential for writing high‑quality, efficient code. Stay tuned to the public account for more Python tutorials.